Rubber mixer



July 3, 1962 w. A. CLARK RUBBER MIXER Filed April 16, 1959 H H P; III will} [I'll Z4 2 Sheets-Sheet 1 FIG. I

INVENTOR. WILLIAM A. CLARK ATTORNEY States Unite This invention relates to rubber mixers and, more particularly, to rubber mixers of the Banbury type. The invention is particularly concerned with the provision of an improved form of door for the discharge opening at the bottom of the chamber of such a mixer.

Mixers of this type comprise what is usually referred to as a double cylinder chamber. The chamber consists of two cylinders placed side by side with their axes parallel horizontal relation, the cylinders communicating with each other at the portions thereof lying between their axes. A rotor is provided in each of the cylinders, each of the rotors being provided with blades, the tips of which approach closely to the walls of the respective cylinders as they rotate. The chamber formed by the two communicating cylinders is provided with a bottom discharge opening at its center which extends lengthwise across the center and a sliding door is provided toclose this opening so that after a batch of rubber or other plastic material has been treated in the machine by the rotating cylinders, the door may be moved outwardly to an open position to allow the batch of material to drop by gravity from the chamber.

In the past, doors of this type have been formed with a smooth upper surface to fit tightly against the sides of the openings in the cylinders with a suflicient clearance to allow the door to operate.

Doors of prior mixers of this type were made with the above mentioned clearance because it was found that with any less clearance, the doors were galled by the rollers during opening and closing of the doors. By providing the improved door, the end seals can be made tight and, yet, the clearance between the door and rollers can be made of a desirable magnitude and galling during opening and closing of the door can be eliminated.

In these mixers, it is necessary that the cylinder rotate in close proximity to the upper surface of the discharge door in order to perform a thorough job of mixing; however, there must be a clearance between the cylinder and the door in order for the machine to operate satis factorily. It is also desirable to have the end surfaces of the door where they form a seal with the side of the frame of the machine formed of flat surfaces converging at a point in order to conveniently provide a thorough seal at this point.

It will be understood that these machines are often perated under considerable pressure, the pressure being applied either by a forward plunger or floating weight mounted in the charging stack. It is necessary, therefore, thatthe door fit tightly at all engaging surfaces to form a complete closure for the chamber and to prevent leakage of the material therethrough.

It is, accordingly, an object ofthe present invention to provide a new and improved mixer for plastic mate rials.

Another object of the iuvention'is to provide a mixer for plastic materials having a bottom discharge opening and a novel form of door for closing the opening.

Still another object of the invention is to provide a mixer for plastic materials of the type described, the chamber of the mixer comprising a movable door or closure member having two flat upper surfaces which stem 1 "ice meet in a straight line at each end of the door, these surfaces fitting tightly against correspondingly shaped surfaces provided upon the end walls of the chamber and providing a clearance at an intermediate point.

Yet another object of the invention is to provide an improved mixer door according to the above description wherein the intermediate part of the door has flat surfaces which meet in a curved line in-between the fiat end surfaces which form a seal between the door and the chamber of the machine.

A further object of the invention is to provide an improved door wherein the two flat surfaces of the intermediate part of the door end at a flat planar horizontal intermediate surface thereof and the end surfaces of the door converge to an apex at the ends thereof.

With the above and other objects in view, the present invention consists of the combination and arrangement of parts hereinaftermore fully described, illustrated in the accompanying drawings and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportions, and minor details of construction without departing from th spirit or sacrificing any of the advantages of the inven tion.

In the drawings:

FIG. 1 is a side elevational view of a mixer embodying the invention, some parts thereof being broken away to show the interior of the mechanism;

FIG. 2 is a cross sectional View taken on line 2-2 of FIG. 1;

FIG. 3 is an enlarged sectional view similar to that shown in FIG. 2;

FIG. 4 is an isometric view of the improved door;

FIG. 5 is a cross sectional view of another ment of the invention;

FIG. 6 is a cross sectional view of still another embodiment of the invention; and

FIG. 7' is a view of another embodiment of the invention.

Now with more specific reference tov the drawings, FIGS. 1 to 4 inclusive show a mixer comprising a chamber 10 having a charging stack 11 at the upper portion thereof. The charging stack 11. is provided with end walls 12 which are continued downwardly to form the end walls or end plates for the chamber 10..

The chamber 10 is of the double cylindrical type consisting of two cylinders 13 and 14, in each of which is mounted a bladed rotor 15. The cylinders 13 and 14 communicate with each other at their adjacent portions so as to form a chamber of substantially double cylindrical shape. At the lower portion of the chamber and at the central portion thereof is provided a discharge opening 16. The opening 16 is closedby a door 17 which is slidably mounted to be moved to an open and a closed position. a

The door or-closure member 17 is keyed or otherwise secured to a cylinder 18. The cylinder 18 is provided with wings 1'9 adapted to extend laterally over ways 20. The ways 20 are provided on lower base portions 21 of the chamber 10. The door 17 is adapted to be moved to open and closed positions by means of fluid pressure introduced into opposite ends of the cylinder 18. -The fluid pressure works against a piston 23 mounted on a piston rod 24. The outer end of the piston rod 24 is rigidly held in a base portion 26 of the mixer at 25. As the piston 23 is thus fixed against longitudinal movement, the introduction of fluid pressure upon one side or the other of the piston 23 will affect movement of the cylinder 18 and the door 17 selectively in opposite directions to open and closed positions.

It will be noted that a line 36 which denotes the apex of the intermediate part of the door or closure member 17 embodithe door. and the frame.

. lows: V l. A mixer for heavy plastic materials comprising a double cylindrical chamber having a bladed rotor in each isconsiderably below an upper line 35 of the end portions of the door 17. This may be, for example, at aclearance distanceof .010" therefrom. It is necessary for the rotor to clear the door by approximately .010 inch during operation. By relieving the intermediate part of the door between the ends, the rotor canhave the proper operating clearance between its periphery and the door and, yet, the ends of the door will fit against the fixed machine frame as tightly as if the rotor cleared the door by only .005 inch; Therefore, the rotor can rotate freely at a proper clearance; yet a minimum clearance is provided between the'ends of the door and the machine frame so that a minimum amount of material can escape between disclosed in Patent No. 2,615,689, there had to be .010

'inch'cl'earance between the door and theframe'in order to provide the proper clearance between the rotor and the door. Therefore, considerable material could leak out between the ends ofthe door and the rotor. In the pres ent design, leakage of dust and compounds is reduced, yet the rotor can have the proper clearance between it and the door, yet permitting the, same case of opening and In the embodiment of the invention shown in FIG. 5, 30

a door 117 is shown with side surfaces 133 and 134 at the intermediate part thereof. The side surfaces 133 and 134 meet an intermediate horizontal surface 136. End

surfaces 131 and 132 are raised from the surfaces 133 and 134 by approximately .010 inch and these surfaces meet at an apex 135 so that the surfaces 131 and 132 form a firm seal withrthe'end frames of the machine; The cylinder, therefore, can be operated at a smaller clearance Formerly, with doorssuch as I closure member for said opening, the upper side of said her to form a closure, the upper sides of said member at the ends thereof being parallel to the intermediate portions and disposed a short distance thereabove, said upper sides being adapted to be in close proximity to said downwardly. disposed surfaces.

2. Amixer for heavy plastic materials comprising a double cylindrical chamber having a bladed rotor in each of the cylinders thereof, said chamber being provided with I a common discharge opening, and a movably mounted closure member for said opening, said member having a sharply defined ridge upon its upper surface and downwardly sloping plane areas on each side of said ridge, said chamber being provided with end walls having lower surfaces fitting snugly against said plane areas, said ridge beingparallel to the axes of said rotors and being disposed between the blades of said rotors and a substantial distance below the planes of said axes, the upper sides of said member at the ends thereof being parallel to the intermediate portions and disposed a short distance thereabove.

3. A mixer for heavy plastic materials comprising a double cylindrical chamber having a bladed rotor in each of the cylinders thereof, said chamber being provided with to the surfaces 133 and 134 than would be possible without the. end surfaces being built up as shown;

The'hori .zontal surface 136 allows room above the door 117' for a bottom discharge opening, and a slid-ably mounted closure member for said opening, the upper side of said member comprising two plane surfaces meeting at a line substantially centrally of said chamber, said surfaces sloping upwardly from the side edges of said closure member to a horizontal surface, said horizontal surface lying between the blades of said. rotors and in a horizontal plane 7 intermediate the plane of said rotors and the lower porend surfaces 231 and 232 are built up approximately .010

in'chabove intermediate surfaces 233 and234. A door 217 is. provided which is, in general, like the doors 17 and 117 shown in FIGS. 1 to 5; however, the surfaces 233 V and 234 converge into a curved upper top surface 236.

and 334 out down approximately .OOSinch below surfaces.

331 and332. The door 317 has the'upwardly curving side surfaces 331 and 332 terminating at a fiat surface 335. Theintermediate part of the top surface 336 of the door 3'17 is cut down or relieved, thus eliminating galling during opening of the. door 317.

The foregoing specification sets forth the invention in its preferred. practical forms but the structure shown is cap'able of modification within a range of equivalents with.- out departing from the invention which is to be understood a is broadly novel as is commensurate with the appended claims. I

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as folof the cylinders thereof, said chamber being provided with a bottom discharge opening, andaslidably mounted tions of said cylinders, the upper sides of said member at the ends thereof being parallel to the intermediate portions and disposed a short distance thereabove.

4. A mixer for heavy plastic materials comprising a double cylindrical chamber having a bladed rotor in each of the cylinders thereof, said chamber being provided with a'bottom discharge opening, and a slidably mounted closure member for said opening, the upper side of said member comprising two plane surfaces meeting at a line substantially centrally of said chamber, said surfaces sloping upwardly from the side edges of said closure memrotors and the lower portions of said cylinders, said side edges merging into said curved surface, the upper sides of said member at the ends thereof being parallel to the intermediate portions and disposed a short distance thereabove.

5. A mixer for heavy plastic materials comprising a double cylindrical chamber having a bladed rotor in each of the cylinders thereof, said chamber being provided with a bottom discharge opening, and a movably mounted closure member for said opening, said chamber being provided with end walls having lower surfaces fitting snugly against plane areas of a ridge, said ridge being parallel to the axes of said rotors and being disposed between the blades of said rotors and a substantial distance below the plane of said axes, the upper sides of said member at the ends thereofbeing parallel to the intermediate portions and disposed a short distance thereabove.

6. .A mixer for heavy plastic materials comprising a double cylindrical chamber having a bladed rotor in each of the cylinders thereof, said chamber being provided with a bottom discharge opening and a movably mounted closure member for said opening, said member having downwardly sloping plane areas on each side thereof, said chamber beingprovided with end walls having lower surfaces fitting snugly against said plane areas, a ridge, said ridge being parallel to the axes'of said rotors and being disposed between the blades of said rotors and a substantial distance below the plane of said axes, the upper sides of said member at the ends thereof being parallel to the intermediate portions and disposed a short distance thereabove.

7. A mixer for heavy plastic materials comprising a double cylindrical chamber having a bladed rotor in each of the cylinders thereof, said chamber being provided with a' bottom discharge opening, and a slidably mounted closure member for said opening, the upper side of said member comprising two convex surfaces generally coextensive with the outside surfaces of said rotors, said surfaces sloping upwardly fromthe side edges of said closure member toga ridge, said ridge lying between the blades of said rotors and in a horizontal plane intermediate the plane of said rotors and the lower portions of said cylinders, downwardly disposed surfaces on said mixer at the ends of said chamber lying in planes tangent to said cylindrical chamber and adapted to cooperate with said closure member to form a closure, the upper sides of said memher at the ends thereof being parallel to the intermediate portions and disposed at short distance thereabove, said upper sides being adapted to be in close proximity to said downwardly disposed surfaces.

References Cited in the file of this patent UNITED STATES PATENTS I 1,836,355 Banbury Dec. 15, 1931 2,615,689 Schnuck et a1. Oct. 28, 1952 2,725,220 Hale et al. Nov. 29, 1955 

